A battery charging device of the present invention has a rectifier portion that is formed by switching elements, and performs advance angle/delay angle control. An advance angle/delay angle amount in the advance angle/delay angle control is determined based on a differential voltage between the voltage of a battery and a predetermined target voltage. In this case, when a determined delay angle amount exceeds a delay angle limit value, delay angle control is performed using the delay angle limit value. Moreover, the power generation amount of an alternating current generator is detected, and the delay angle amount and power generation amount are stored. If the current delay angle amount is greater than the previous delay angle amount, and the previous power generation amount is greater than the current power generation amount, then the previous delay angle amount is set as the delay angle limit value.